Polarizer, method for manufacturing the same, optical film and image display

ABSTRACT

A polarizer of the present invention is composed of a film comprising a structure in which fine metallic particles is dispersed in a polymer matrix is characterized in that a polymer forming the polymer matrix is a translucent polymer having a transmittance of 88% or more when measured thereof with a thickness of 1 mm and the film is uniaxially stretched. The polarizer is good in heat resistance and transmittivity.

TECHNICAL FIELD

This invention relates to a polarizer and a fabrication method therefor.The invention further relates to a polarizing plate and an optical filmcomprising the polarizer. The invention still further relates to animage display such as a liquid crystal display, an organic EL display orPDP comprising the polarizer, the polarizing plate or the optical film.

BACKGROUND ART

An image display such as a liquid crystal display employs a polarizer(polarizing plate) according to the underlying principle of thedisplays. In company with progress to a large-sized image display or adiversification of functionality thereof in recent years, the demand forpolarizers have been on the rise and at the same time, requirements forbetter quality and improved durability have been more and moreincreasing. Especially, very high heat resistance has been required inapplications to the liquid crystal displays, which are assumed to beused in a severe environment outdoors, used in a cellular phone, a PDAand the like; and to the liquid crystal displays used in a vehiclenavigation and a liquid crystal projector.

Conventionally, as a polarizer for an image display, there has beenwidely employed mainly a polarizer fabricated by dyeing a stretchedpolyvinyl alcohol film with a dichroic material such as iodine or a dye,which has the property of dichroism (see, for example, JP-A No.2001-296427).

An iodine-based polarizer is obtained in a procedure in which a film isdyed with an aqueous solution containing amorphous iodine, followed bystretching, has a high polarizability for visible light and can befabricated as a large-sized polarizer. However, in the iodine-basedpolarizer iodine sublimes at a high temperature or its complex structureis altered, which makes it difficult to maintain a polarizationperformance. On the other hand, a dye-based polarizer using a dichroicdye is better in heat resistance as compared with the iodine-basedpolarizer, whereas the polarizer has not been widely employed withlimited applications thereof because of insufficient dichroic ratio of adye used therein and poor weather resistance thereof. Note that inaddition to polyvinyl alcohols, examples of film materials of apolarizer include: polystyrenes, cellulose derivatives, polyvinylchlorides, polypropylenes, acrylic-based polymers, polyamides,polyesters, saponified products of ethylene-vinyl acetate copolymers andothers.

A polarizer fabricated by dispersing metallic particles havinganisotropy in light absorption property on an isotropic substrate isadopted as a polarizer used in the field of optical devices such as anoptical communication device and an optical recording reproductiondevice requiring a heat resistance at a high temperature. As such apolarizer, there has been adopted, for example, a polarizer fabricatedin a procedure in which metal particles are deposited in glass through areduction reaction or the like, followed by stretching. A polarizerobtained by dispersing fine metallic particles on an isotropic substrateis not suited for mass production because fine metallic particles aredeposited with a vacuum deposition method or the like, which requires ahigh temperature heating process.

It has been known that a film in which fine metallic particles havinganisotropy are dispersed in polyimide are uniaxially stretched tothereby obtain a polarization film good in heat resistance (see, forexample, JP-A No. 8-184701). Since such a polarizing film is, however,made form polyimide, the film has a problem of yellowing even afteruniaxially stretching and poor in transmittivity.

A polarizer using a dichroic material described above to which iodinebelongs exerts a polarization performance by aligning the dichroicmaterial along a stretch direction. Absorption spectra measured whenpolarized light enters on such a polarizer generally include anabsorption spectrum (MD spectrum) with an incident polarization plane inparallel to a stretch direction of the polarizer and an absorptionspectrum (TD spectrum) with an incident polarization plane in parallelto a direction perpendicular to the stretch direction of the polarizer,wherein both have the same spectral line shape as each other (almost thesame absorption peak wavelength) and a relation in absorbance of MDspectrum>TD spectrum. That is, “the absorption peak of an absorptionspectrum shifts longitudinally” depending on an azimuth of the incidentpolarization plane relative to a polarizer. In order to enhance apolarization performance, it is required that an absorbance at theabsorption peak in the MD spectrum is increased, while an absorbance atthe absorption peak in the TD spectrum is decreased to the lowestpossible value. That is, it has been necessary to increase a differencein absorbance between the MD spectrum and the TD spectrum to the maximumpossible value.

DISCLOSURE OF INVENTION

It is an object of the invention to provide a polarizer capable of beingfabricated with a simple and ease method, and good in heat resistance,and a fabrication method therefor.

It is another object of the invention to provide a polarizer good inheat resistance and transmittivity, and a fabrication method therefor.

It is still another object of the invention to provide a polarizer goodin polarization performance in a case where a difference in absorbancebetween the MD spectrum and TD spectrum is small.

It is further another object of the invention to provide a polarizingplate comprising the polarizer and to provide an optical film comprisingthe polarizer, or the polarizing plate. It is a further object of theinvention to provide an image display comprising the polarizer, thepolarizing plate or the optical film.

The inventors, in order to solve the problems, have conducted seriousstudies with the following findings that the objects can be achievedwith a polarizer shown below, which has led to completion of theinvention.

The invention (1) is related to a polarizer composed of a filmcomprising a structure in which fine metallic particles is dispersed ina polymer matrix,

wherein a polymer forming the polymer matrix is a translucent polymerhaving a transmittance of 88% or more when measured thereof with athickness of 1 mm and the film is uniaxially stretched.

Since the polarizer of the invention has a structure in which fine ametallic particle is dispersed in a polymer matrix, the polarizer has aheat resistance when used as an image display and is preferably adoptedin applications requiring a heat resistance. A translucent polymerhaving a transmittance of 88% or more is used in the polymer matrix,which renders a transmittivity of the matrix good. The higher thetransmittance of a translucent polymer is, the more the polymer ispreferred and the transmittance is preferably 88% or more and morepreferably 90% or more. The transmittance of a translucent polymer is atotal light transmittance when measured on a film formed therewith to athickness of 1 mm with UV-3150 manufactured by SHIMADZU CORPRATION.

It is estimated that fine metallic particles dispersed in a polymermatrix causes a surface plasmon absorption to thereby absorb light of acertain wavelength, and it is further thought that since a translucentpolymer, which is a medium, has uniaxial birefringence due to uniaxialstretching, the stretched polymer exerts an optical anisotropy andthereby, a polarizer of the invention reveals a polarizationcharacteristic. A plasmon absorption is caused by resonance between anoscillation of incident light at an interface of a fine particle and aplasma oscillation of electrons in the fine particle, in which situationthe metal exhibits a large light absorption characteristic. Since awavelength region having a polarization characteristic is determined bya plasmon absorption wavelength of fine metallic particles and arefractive index of a translucent polymer, which is a medium, apolarizer with any optical characteristic can be designed by using abirefringence of the translucent polymer. While iodine or a dichroic dyeis usually used as an absorption material, a metal is, in the invention,used as an absorption material using a characteristic of fine metallicparticles.

In the polarizer, a domain formed with fine metallic particlespreferably has an average particle diameter of 100 nm or less, and anaspect ratio (a ratio of the maximum length/the minimum length) of 2 orless. That is, the domain is preferably a near sphere with no anisotropyin shape. This is because if the aspect ratio exceeds 2, major axes offine metallic particles is necessary to be aligned in an alignmentdirection when alignment of the fine metallic particles is required,whereas if the aspect ratio is 2 or less, no necessity arises for a stepof aligning the particle with respect to a major axis and minor axis. Anaverage particle diameter of the domain is preferably 100 nm or less andmore preferably 50 nm or less. The aspect ratio is preferably 2 or less,more preferably 1.8 or less, and further more preferably 1.5 or less.Note that description will be given of details of an average particlediameter of domains and the aspect ratio of fine metallic particles inexamples.

The invention is directed to a fabrication method for the polarizer,comprising steps of: forming a film with a mixed solution comprisingfine metallic particles obtained by dispersing fine metallic particlesin a solution containing a translucent polymer having a transmittance of88% or more when measured thereof with a thickness of 1 mm andthereafter, uniaxially stretching the film.

A polarizer of the invention is good in heat resistance andtransmittance and can be fabricated with a simple and easy method. Sincea wavelength region having a polarization characteristic is determinedby a plasmon absorption wavelength of fine metallic particles and acharacteristic such as a refractive index of a translucent polymer,which is a medium, a polarizer having any optical characteristic can befabricated by properly selecting a translucent polymer, a material offine metallic particles and others and further controlling abirefringence of a film made from the translucent polymer with uniaxialstretching.

The invention (2) is related to a polarizer in which fine metallicparticles is dispersed in a matrix formed with a liquid crystallinematerial. The liquid crystalline material of the polarizer is preferablyuniaxially aligned.

Since the polarizer of the invention has a structure in which finemetallic particles is dispersed in a matrix, the polarizer has a heatresistance in a case where it is used as an image display and preferablyadopted in applications where a heat resistance is required. A polarizerof the invention with such a structure can be fabricated with a simpleand easy method. The liquid crystalline material is preferably a liquidcrystal polymer since a fabrication method in the case is simple andeasy.

It is estimated that fine metallic particles dispersed in a matrixcauses a surface plasmon absorption and thereby absorbs light of acertain wavelength, and a liquid crystalline material, which is amedium, exerts an optical anisotropy and it is thought that a polarizerof the invention thereby reveals a polarization characteristic. APlasmon absorption is caused by resonance between an oscillation ofincident light at an interface of a fine particle and a plasmaoscillation by electrons in the fine particle, in which situation metalexhibits a large absorption characteristic. Since a wavelength regionhaving a polarization characteristic is determined by a plasmonabsorption wavelength of fine metallic particles and characteristicssuch as a refractive index of a liquid crystalline material, which is amedium, a polarizer with any optical characteristic can be designed byusing a birefringence of the liquid crystalline material. While iodineor a dichroic dye is usually employed as an absorption material, a metalis, in the invention, used as an absorption material using acharacteristic of fine metallic particles.

In the polarizer, a domain formed with fine metallic particlespreferably has an average particle diameter of 100 nm or less, and anaspect ratio (a ratio of the maximum length/the minimum length) of 2 orless. That is, the domain is preferably a near sphere with no anisotropyin shape. This is because if the aspect ratio exceeds 2, major axes offine metallic particles is necessary to be aligned in an alignmentdirection when alignment of the fine metallic particles is required,whereas if the aspect ratio is 2 or less, no necessity arises for a stepof aligning the particle with respect to a major axis and minor axis. Anaverage particle diameter of the domain is preferably 100 nm or less andmore preferably 50 nm or less. The aspect ratio is preferably 2 or less,more preferably 1.8 or less, and further more preferably 1.5 or less.Note that description will be given of details of an average particlediameter of domains and the aspect ratio of fine metallic particles inexamples.

The invention is related to a fabrication method for the polarizer,comprising step of: forming a film with a mixed solution obtained bydispersing fine metallic particles in a solution containing a liquidcrystalline material.

According to the fabrication method, a polarizer good in heat resistancecan be obtained with a simple and easy way. Since a wavelength regionhaving a polarization characteristic is determined by a plasmonabsorption wavelength of fine metallic particles and characteristicssuch as a refractive index of a liquid crystalline material, which is amedium, a polarizer with any optical characteristic can be fabricated byproperly selecting a liquid crystalline material, fine metallicparticles and others and controlling a birefringence of a film formedwith the liquid crystalline material.

The invention (3) is related to a polarizer having an absorptionspectrum with an absorption peak at a given wavelength, measured whenpolarized light impinges thereon,

-   -   wherein if an azimuth of an incident polarization plane is        altered relative to the polarizer, the absorption peak        wavelength shifts in accordance with an alteration in the        azimuth.

In this way, in the polarization absorption spectrum of a polarizer ofthe invention, a value of the absorption peak wavelength itself altersdepending on an azimuth of an incident polarization plane. That is, “anabsorption spectrum shifts an absorption peak laterally” depending on anazimuth of the incident polarization plane relative to the polarizer. Asa result of the shift, a good polarization performance can be exerteddepending on an azimuth of the incident polarization plane even with asmall difference in absorbance between the MD spectrum and the TDspectrum. Note that measurement of an absorption spectrum is detailed inthe examples.

In the polarizer, generally, in a case where an azimuth of the incidentpolarization plane relative to the polarizer is altered, if an azimuthof the incident polarization plane is 0 degree when an absorption peakwavelength of an absorption spectrum that is measured is the longestwavelength, which is referred to as λ1, by definition,

-   -   if an azimuth of the polarization plane is gradually increased        from 0 degree, a value of the absorption peak wavelength shifts        to the short wavelength side in company with the increase and

when an azimuth of the incident polarization plane is 90 degrees, avalue of the absorption peak wavelength is the shortest wavelength,which is referred to as λ2, by definition. A polarizer of the inventionusually has the absorption peak wavelength in the MD spectrum as thelongest wavelength (λ1), and as an azimuth of the incident polarizationplane is rotated with the azimuth corresponding the MD spectrum as areference, the absorption peak wavelength of a polarization spectrumgradually shifts to the short wavelength side and when the rotationreaches 90 degrees (the TD spectrum), the peak wavelength takes theshortest wavelength (λ2) or vice versa.

The polarizer preferably satisfies a relation of (λ1−λ2)=10 to 50 nm andmore preferably a relation of (λ1−λ2)=20 to 50 nm. If the value of(λ1−λ2) is less than 10 nm, two absorptions to be shifted are almostsuperimposed one on the other, which makes it difficult to exert apolarization characteristic.

An absorption characteristic of a polarizer of the invention asdescribed here is clearly different from an absorption characteristic ofan iodine-based polarizer or a polarizer using a dichroic dye.

The polarizer of the invention that is used can be a polarizer in whichfine metallic particles is dispersed in an organic matrix having abirefringence in the film plane.

It is estimated that fine metallic particles dispersed in the organicmatrix cause a surface plasmon absorption and thereby absorbs light of acertain wavelength, so that a polarization characteristic exerted by thepolarizer is obtained. A Plasmon absorption is caused by resonancebetween a oscillation of incident light at an interface of a fineparticle and a plasma oscillation by electrons in the fine particle, inwhich situation metal exhibits a large absorption characteristic. Theabsorption characteristic is determined by a plasmon absorptionwavelength of fine metallic particles and characteristics such as arefractive index of an organic material, which is a medium, and adispersion state of domains made of fine metallic particles. Hence, in acase where a refractive index is different according to an azimuth in asurface of a film (that is, in a case of a birefringent medium), theabsorption characteristic is different according to an azimuth of theincident polarization plane and a shift in wavelength therefore occurs.It is thought that anisotropy in absorption, that is a polarizationperformance, is revealed according to a principle described above.

Since a polarizer of the invention has a structure in which finemetallic particles is dispersed in a matrix, it has a heat resistancewhen being used as an image display. Therefore, a polarizer of theinvention is preferable in applications, in which very high heatresistance has been required, to liquid crystal displays, which areassumed to be used in a severe environment outdoors, including liquidcrystal displays such as a cellular phone and a PDA; and liquid crystaldisplays such as vehicle navigation and a liquid crystal projector.

The organic matrix is formed with a polymer matrix, a polymer formingthe polymer matrix is a translucent polymer having a transmittance of88% or more when measured thereof with a thickness of 1 mm, and the filmis a uniaxially stretched can be preferably used as the film.

An organic matrix that is used is preferably formed with a liquidcrystalline material. A liquid crystalline material is preferablyuniaxially aligned. A liquid crystalline material is preferably a liquidcrystal polymer because of simplicity and ease in fabrication method.

In the polarizer, a domain formed with fine metallic particlespreferably has an average particle diameter of 100 nm or less, and anaspect ratio (a ratio of the maximum length/the minimum length) of 2 orless. That is, the domain is preferably a near sphere with no anisotropyin shape. This is because if the aspect ratio exceeds 2, major axes offine metallic particles is necessary to be aligned in an alignmentdirection when alignment of fine metallic particles is required, whereasif the aspect ratio is 2 or less, no necessity arises for a step ofaligning the particle with respect to a major axis and minor axis. Anaverage particle diameter of the domain is preferably 100 nm or less andmore preferably 50 nm or less. The aspect ratio is preferably 2 or less,more preferably 1.8 or less, and further more preferably 1.5 or less.Note that description will be given of details of an average particlediameter of domains and the aspect ratio of fine metallic particles inexamples.

Note that an alteration in the absorption peak according to an azimuthof the incident polarization plane of a polarizer of the invention isalso controlled by a distribution state of domains formed with finemetallic particles in addition to anisotropy in refractive index of amatrix material.

The invention is related to a polarizing plate in which a transparentprotective layer is provided on at least one surface of the polarizer.The invention is further related an optical film comprising at least onepolarizer or the polarizing plate as a laminate. The invention is stillfurther related to an image display comprising the polarizer, thepolarizing plate or the optical film.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 shows absorption spectra measured while altering an azimuth of anincident polarization plane, in a polarizer of Example 1.

BEST MODE FOR CARRYING OUT OF THE INVENTION

A polarizer of the invention is formed with an organic matrix having abirefringence. Examples of organic matrix materials include: a filmobtained by uniaxially stretching a non-liquid crystal polymer(translucent polymer); a film obtained by uniaxially aligning a liquidcrystalline material and others.

A translucent polymer that is used preferably has a transmittance of 88%or more when measured on a sample thereof with a thickness of 1 mm. Anyof translucent polymers each with a transmittance in the range can beused without placing any specific limitation thereon.

Examples of translucent polymers include: polyvinyl alcohol or aderivative thereof. As derivatives of polyvinyl alcohol, polyvinylformals, polyvinyl acetals, etc. may be mentioned, and in additionderivatives modified with olefins, such as ethylene and propylene, andunsaturated carboxylic acids, such as acrylic acid, methacrylic acid,and crotonic acid, alkyl esters of unsaturated carboxylic acids,acrylamides etc. may be mentioned. A polymerization degree of polyvinylalcohol that can be generally used is about 1000 to 10000 and asaponification thereof is about 80 to 100 mol %.

Note that additives such as a plasticizer can also be added into thepolyvinyl alcohol-based resin film. Examples of plasticisers include:polyols and condensates thereof such as glycerin, diglycerin,triglycerin, ethylene glycol, propylene glycol, polyethylene glycol andothers. No limitation is placed on a content of a plasticizer and thecontent is preferably 20 wt % or less in the polyvinyl alcohol-basedresin film.

Examples of translucent polymers include: polyester-based resins such aspolyethylene terephthalate and polyethylene naphthalate; styrene-basedresins such as polystyrene and acrylonitrile styrene copolymer (ASresin); and olefin-based resins such as polyethylene, polypropylene, apolyolefin with cyclo or norbornene structure and an ethylene propylenecopolymer. Examples further include: a vinyl chloride-based resin, acellulose-based resin, an acrylic-based resin, an amide-based resin, animide-based resin, a sulfone-based polymer, a polyether sulfone-basedresin, a polyether ether ketone-based resin polymer, a polyphenylenesulfide-based resin, a vinylidene chloride-based resin, a vinylbutyral-based resin, an allylate-based resin, a polyoxymethylene-basedresin, a silicone-based resin, a urethane-based resin and others. Thetranslucent polymers can be used either alone or in combination of twokinds or more. A translucent polymer can also be used with a curedproduct of a thermoset resin or an ultraviolet curing resin such as aphenol-based, a melamine-based, an acrylic-based, a urethane-based, anacrylic urethane-based, an epoxy-based or a silicone-based resin.

A film formed with a translucent polymer is imparted a uniaxialbirefringence by in a uniaxial stretch treatment. Therefore, preferableis a translucent polymer having an anisotropy causing a birefringencewith ease and preferable examples thereof include polyvinyl alcohol,polycarbonate, a sulfone-based polymer and others.

A liquid crystalline material may be a low molecular weight liquidcrystal or a high molecular weight liquid crystal (liquid crystalpolymer) or may be an active energy ray curing polymerizable liquidcrystal (a liquid crystal monomer). A liquid crystal polymer is aligned,for example, by heating or the like and then cooled and fixed to form amatrix. A liquid crystal monomer is polymerized by irradiation with anenergy ray such as ultraviolet after alignment thereof to thereby amatrix.

A liquid crystalline material mentioned above may be a compoundexhibiting a liquid crystallinity at a room temperature, a lyotropicliquid crystal, a thermotropic liquid crystal or a compound exhibitingliquid crystallinity at a high temperature. As liquid crystallinematerials, preferably used are liquid crystalline materials revealing anematic phase or a smectic phase. The liquid crystalline materials canbe used either alone or in mixture of two or more kinds.

As the above-mentioned liquid crystal polymers, polymers having variousskeletons of principal chain types, side chain types, or compoundedtypes thereof may be used without particular limitation. As principalchain type liquid crystal polymers, polymers, such as condensed polymershaving structures where mesogen groups including aromatic units etc. arecombined, for example, polyester based, polyamide based, polycarbonatebased, and polyester imide based polymers, may be mentioned. As theabove-mentioned aromatic units used as mesogen groups, phenyl based,biphenyl based, and naphthalene based units may be mentioned, and thearomatic units may have substituents, such as cyano groups, alkylgroups, alkoxy groups, and halogen groups.

As side chain type liquid crystal polymers, polymers having principalchain of, such as polyacrylate based, polymethacrylate based,poly-alpha-halo acrylate based, poly-alpha-halo cyano acrylate based,polyacrylamide based, polysiloxane based, and poly malonate basedprincipal chain as a skeleton, and having mesogen groups includingcyclic units etc. in side chains may be mentioned. As theabove-mentioned cyclic units used as mesogen groups, biphenyl based,phenyl benzoate based, phenylcyclohexane based, azoxybenzene based,azomethine based, azobenzene based, phenyl pyrimidine based, diphenylacetylene based, diphenyl benzoate based, bicyclo hexane based,cyclohexylbenzene based, terphenyl based units, etc. may be mentioned.Terminal groups of these cyclic units may have substituents, such ascyano group, alkyl group, alkenyl group, alkoxy group, halogen group,haloalkyl group, haloalkoxy group, and haloalkenyl group. Groups havinghalogen groups may be used for phenyl groups of mesogen groups.

Besides, any mesogen groups of the liquid crystal polymer may be bondedvia a spacer part giving flexibility. As spacer parts, polymethylenechain, polyoxymethylene chain, etc. may be mentioned. A number ofrepetitions of structural units forming the spacer parts is suitablydetermined by chemical structure of mesogen parts, and the number ofrepeating units of polymethylene chain is 0 through 20, preferably 2through 12, and the number of repeating units of polyoxymethylene chainis 0 through 10, and preferably 1 through 3.

The above-mentioned liquid crystal polymers preferably have glasstransition temperatures of 50° C. or more, and more preferably 80° C. ormore. Furthermore they have approximately 2,000 through 100,000 ofweight average molecular weight.

As liquid crystalline monomers, monomers having polymerizable functionalgroups, such as acryloyl groups and methacryloyl groups, at terminalgroups, and further having mesogen groups and spacer parts including theabove-mentioned cyclic units etc. may be mentioned. Crossed-linkedstructures may be introduced using polymerizable functional groupshaving two or more acryloyl groups, methacryloyl groups, etc., anddurability may also be improved.

No specific limitation is placed on a kind of fine metallic particlesdispersed in the matrix to form domains and any of kinds of fine metalparticles may be employed as far as each of the kinds has absorption inthe visible region. Examples of metals include: silver, copper, gold,platinum, aluminum, palladium, rhodium, iron, chromium, nickel,manganese, tin, cobalt, titanium, magnesium, lithium and others, andalloys of two or more kinds of the metals as elements. The metals aselements and alloys thereof can be used in combination of plural kindsthereof.

A content of fine metallic particles dispersed in a matrix is preferably0.1 to 10 parts by weight and more preferably 0.5 to 5 parts by weightrelative to 100 parts by weight of the matrix materials in order toattain a polarizer good in heat resistance and transmittivity. Domainsformed with fine metallic particles in a polymer matrix or a liquidcrystalline material are not, as described above, preferably aligned ina specific direction and an average particle diameter of fine metallicparticles is preferably 100 nm or less and an aspect ratio thereof ispreferably 2 or less.

Fine metallic particles in the initial state can be replaced with ametallic dopant capable of forming fine metallic particles by reductionand deposition or the like. A metallic dopant can deposit fine metallicparticles and fine metallic particles can be dispersed in a process inwhich the metallic dopant is mixed into a solution containing an organicmatrix material, followed by reduction or the like. It is only requiredin order for a metallic dopant to be usable that a metallic dopant canbe dissolved in a solution of the organic matrix material and hasabsorption in the visible light region and examples thereof are asfollows: The examples thereof, include: an inorganic metal compound, anorganic metal compound and a complex of an inorganic metal compound andan organic metal compound, and a complex of organic metal compounds. Theexamples thereof, to be more detailed, include: a metal halide, a metalnitrate, a metal acetate, a metal trifluoroacetate, a metalacetylacetonate, a metal trifluoroacetylacetonate, a metalhexafluoroacetylacetonate and others. Further examples thereof that canbe used include: complexes obtained by mixing the compounds mentionedabove individually into acetyl acetone, 1,1,1-trifluoroacetylacetone or1,1,1,5,5,5-hexafluoroacetylacetone.

No specific limitation is placed on a fabrication method for a polarizerof the invention and fine metallic particles are dispersed into asolution containing a matrix material to thereby prepare a mixedsolution. A mixing ratio of a solution of an organic matrix material anda solution in which fine metallic particles are dispersed (or a solutioncontaining a metallic dopant) is adjusted properly so that a content offine metallic particles dispersed in the matrix in the obtainedpolarizer falls within the above-mentioned range. Note that thefollowing various kinds of additives can be added into the solution: adispersant, a surfactant, a hue adjuster, an ultraviolet absorbent, aflame retardant, an antioxydant, a thickner, a plasticizer and others.

In a case where an organic matrix material is a translucent polymer, afilm is formed with the mixed solution and thereafter, a polarizer isobtained by uniaxially stretching.

No specific limitation is placed on a solvent used in a translucentpolymer solution as far as the solvent dissolves a translucent polymer.Examples thereof include: water; aromatic hydrocarbons such as tolueneand xylene; ketones such as acetone, methyl ethyl ketone, methylisobutyl ketone, cyclohexanone, cyclopetanone, cycloheptanone,2-heptanone, methyl isobutyl ketone and butyl lactone; alcohols such asmethanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butylalcohol, iso-butyl alcohol and tert-butyl alcohol; esters such as methylacetate, ethyl acetate, propyl acetate, methyl propionate and ethylpropionate; hydrocarbons such as hexane and cyclohexane; hydrocarbonhalides such as dichloromethane, chloroform, carbon tetrachloride,dichloroethane, trichloroethane, tetrachloroethane andtrichloroethylene; and ethers such as tetrahydrofuran. Note that in acase where a water-soluble polymer such as polyvinyl alcohol is adoptedas a translucent polymer, water is preferably used as a solvent.

A concentration of a translucent polymer solution is usually preferablyabout 5 to 50 wt % and more preferably about 0.05 to 30 wt %. On theother hand, fine metallic particles are usually mixed into thetranslucent polymer solution, as a dispersion solution. A concentrationof fine metallic particles in a dispersion solution is preferablyadjusted to about 0.1 to 15 wt % and more preferably about 0.1 to 10 wt%.

A film is formed with a mixed solution obtained by dispersing finemetallic particles into the translucent polymer solution. Methods forforming a film that can be adopted include: various kinds of methodssuch as a casting method, an extrusion molding method, a laminatemolding method, an injection molding method, a roll molding method and aflow molding method. By adjusting a viscosity of a solution and a dryingspeed in film formation, sizes of domains and dispersibility can also becontrolled.

Then, by uniaxial stretching, a uniaxial birefringence is imparted to atranslucent polymer with which a polymer matrix is formed. Since awavelength region having a polarization characteristic therein isdetermined by a plasmon absorption wavelength of fine metallic particlesand characteristics such as a refractive index of a translucent polymer,an optical characteristic of a polarizer can be controlled bycontrolling a birefringence of the translucent polymer with a uniaxialstretch treatment.

A uniaxial stretch treatment may be either dry stretching such asstretching in air or contact with a metal roll, or wet stretching inwater in a case where a translucent polymer is a water-soluble polymersuch as polyvinyl alcohol. Note that stretching is performed at atemperature in the vicinity of the glass transition temperature of atranslucent polymer at which extension is possible according to a kindof a translucent polymer. No specific limitation is imposed on a stretchratio and a stretch ratio is preferably about 1.05 to 30, morepreferably about 3 to 30 and still more preferably about 5 to 20. Astretch ratio is more preferably about 1.05 to 8 and further preferablyabout 3 to 8.

In a case where a liquid crystalline material is adopted as a matrixmaterial, for example, the mixed solution is prepared and the mixedsolution is caused to be uniaxially aligned and a film is formed withthe mixed solution to obtain a polarizer.

Examples of solvents used in preparation of a solution of a liquidcrystalline material include: hydrocarbon halides such as chloroform,dichloromethane, dichloroethane, tetrachloroethane, trichloroethylene,tetrachloroethylene and chlorobenzene; phenols such as phenol andp-chlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene,methoxybenzene and 1,2-dimethoxybenzene; in addition, acetone, ethylacetate, tert-butyl alcohol, glycerin, ethylene glycol, triethyleneglycol, ethylene glycol monomethyl ether, diethylene glycol dimethylether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone,N-methyl-2-pirrolidone, piridine, triethylamine, tetrahydrofuran,dimethylformaldehyde, dimethylacetoamide, dimethyl sulfoxide,acetonitrile, butylonitrile, carbon disulfide, cyclohexanone and others.A concentration of a liquid crystalline material solution is preferablyadjusted to about 5 to 50 wt % and more preferably about 0.05 to 30 wt%. On the other hand, fine metallic particles are usually mixed into theliquid crystalline material solution as a dispersion medium solution. Aconcentration of fine metallic particles in a dispersion solutionthereof is preferably adjusted to about 0.1 to 10 wt % and morepreferably about 0.01 to 5 wt %.

A film is formed using a mixed solution obtained by dispersing finemetallic particles into a solution of the liquid crystalline material.The liquid crystalline material is uniaxially aligned. Alignment of theliquid crystalline material can be implemented by forming a film on analignment substrate. As an alignment substrate, there can be usedvarious kinds of substrates that have been conventionally known andexamples thereof that can be used include: an alignment substrateprepared with a method in which a alignment film made from polyimide orpolyvinyl alcohol is formed on the substrate as a thin layer, followedby rubbing; a stretched film obtained by stretching a substrate; and analignment film prepared by irradiating a polymer having a cinnamateskeleton or an azobenzene skeleton or a polyimide with polarizedultraviolet.

Examples of methods for coating the mixed solution on the alignmentsubstrate that can be adopted include: a roll coating method, a gravurecoating method, a spin coating method, a bar coating method and others.After coating, a solvent is removed to form a film. In film formation,sizes of domains and dispersibility thereof can also be controlled byadjusting a viscosity of the solution and a drying speed. No specificlimitation is placed on conditions for solvent removal and any set ofconditions may be applied as far as almost all the solvent can beremoved and no part of a film moves like a liquid or flows down. Removalof a solvent generally uses a drying at room temperature, drying in adrying furnace, heating on a hot plate and others.

Alignment of a liquid crystalline material can be achieved by a heattreatment at a temperature at which a liquid crystalline materialassumes a liquid crystal state. The heat treatment temperature isproperly adjusted so as to be adapted for a liquid crystalline material.As a heat treatment method, there can be adopted a method similar to thedrying method. Alignment of a liquid crystalline material can beimplemented by alignment under an influence of an electric field, amagnetic field, a stress or the like in addition to use of an alignmentsubstrate.

In a case where a liquid crystal monomer is adopted as a liquidcrystalline material, the liquid crystalline material is polymerizedafter the alignment. A polymerization initiator is properly mixed into aliquid crystal monomer. As a polymerization method, various kinds ofmeans according to a kind of the liquid crystal monomer and for example,an optical polymerization with irradiation of light can be adopted.Light irradiation is realized with ultraviolet irradiation. Asconditions for ultraviolet irradiation, the irradiation in an inert gasis preferably adopted in order to promote a reaction sufficiently. Ahigh pressure mercury ultraviolet lamp is typically adopted. Differentkinds of lamps can also be used: for example, a metal halide UV lamp andan incandescent lamp.

No specific limitation is placed on a thickness of a polarizer and thethickness is usually about 0.1 to 100 μm and preferably 5 to 80 μm.

The above-described polarizer may be used as a polarizing plate with atransparent protective layer prepared at least on one side thereof usinga usual method. The transparent protective layer may be prepared as anapplication layer by polymers, or a laminated layer of films. Propertransparent materials may be used as a transparent polymer or a filmmaterial that forms the transparent protective layer, and the materialhaving outstanding transparency, mechanical strength, heat stability andoutstanding moisture interception property, etc. may be preferably used.As materials of the above-mentioned protective layer, for example,polyester type polymers, such as polyethylene terephthalate andpolyethylenenaphthalate; cellulose type polymers, such as diacetylcellulose and triacetyl cellulose; acrylics type polymer, such as polymethylmethacrylate; styrene type polymers, such as polystyrene andacrylonitrile-styrene copolymer (AS resin); polycarbonate type polymermay be mentioned. Besides, as examples of the polymer forming aprotective film, polyolefin type polymers, such as polyethylene,polypropylene, polyolefin that has cyclo-type or norbornene structure,ethylene-propylene copolymer; vinyl chloride type polymer; amide typepolymers, such as nylon and aromatic polyamide; imide type polymers;sulfone type polymers; polyether sulfone type polymers; polyether-etherketone type polymers; poly phenylene sulfide type polymers; vinylalcohol type polymer; vinylidene chloride type polymers; vinyl butyraltype polymers; allylate type polymers; polyoxymethylene type polymers;epoxy type polymers; or blend polymers of the above-mentioned polymersmay be mentioned. Films made of heat curing type or ultraviolet raycuring type resins, such as acryl based, urethane based, acryl urethanebased, epoxy based, and silicone based, etc. may be mentioned.

Moreover, as is described in Japanese Patent Laid-Open Publication No.2001-343529 (WO 01/37007), polymer films, for example, resincompositions including (A) thermoplastic resins having substitutedand/or non-substituted imido group is in side chain, and (B)thermoplastic resins having substituted and/or non-substituted phenyland nitrile group in sidechain may be mentioned. As an illustrativeexample, a film may be mentioned that is made of a resin compositionincluding alternating copolymer comprising iso-butylene and N-methylmaleimide, and acrylonitrile-styrene copolymer. A film comprisingmixture extruded article of resin compositions etc. may be used.

As a transparent protection film, if polarization property anddurability are taken into consideration, cellulose based polymer, suchas triacetyl cellulose, is preferable, and especially triacetylcellulose film is suitable. In general, a thickness of a transparentprotection film is 500 μm or less, preferably 1 through 300 μm, andespecially preferably 5 through 300 μm. In addition, when transparentprotection films are provided on both sides of the polarizer,transparent protection films comprising same polymer material may beused on both of a front side and a back side, and transparent protectionfilms comprising different polymer materials etc. may be used.

Moreover, it is preferable that the transparent protection film may haveas little coloring as possible. Accordingly, a protection film having aphase difference value in a film thickness direction represented byRth=[(nx+ny)/2−nz]×d of −90 nm through +75 nm (where, nx and nyrepresent principal indices of refraction in a film plane, nz representsrefractive index in a film thickness direction, and d represents a filmthickness) may be preferably used. Thus, coloring (optical coloring) ofpolarizing plate resulting from a protection film may mostly becancelled using a protection film having a phase difference value (Rth)of −90 nm through +75 nm in a thickness direction. The phase differencevalue (Rth) in a thickness direction is preferably −80 nm through +60nm, and especially preferably −70 nm through +45 nm.

A hard coat layer may be prepared, or antireflection processing,processing aiming at sticking prevention, diffusion or anti glare may beperformed onto the face on which the polarizing film of the abovedescribed transparent protective film has not been adhered.

A hard coat processing is applied for the purpose of protecting thesurface of the polarizing plate from damage, and this hard coat film maybe formed by a method in which, for example, a curable coated film withexcellent hardness, slide property etc. is added on the surface of theprotective film using suitable ultraviolet curable type resins, such asacrylic type and silicone type resins. Antireflection processing isapplied for the purpose of antireflection of outdoor daylight on thesurface of a polarizing plate and it may be prepared by forming anantireflection film according to the conventional method etc. Besides, asticking prevention processing is applied for the purpose of adherenceprevention with adjoining layer.

In addition, an anti glare processing is applied in order to prevent adisadvantage that outdoor daylight reflects on the surface of apolarizing plate to disturb visual recognition of transmitting lightthrough the polarizing plate, and the processing may be applied, forexample, by giving a fine concavo-convex structure to a surface of theprotective film using, for example, a suitable method, such as roughsurfacing treatment method by sandblasting or embossing and a method ofcombining transparent fine particle. As a fine particle combined inorder to form a fine concavo-convex structure on the above-mentionedsurface, transparent fine particles whose average particle size is 0.5to 50 μm, for example, such as inorganic type fine particles that mayhave conductivity comprising silica, alumina, titania, zirconia, tinoxides, indium oxides, cadmium oxides, antimony oxides, etc., andorganic type fine particles comprising cross-linked of non-cross-linkedpolymers may be used. When forming fine concavo-convex structure on thesurface, the amount of fine particle used is usually about 2 to 50weight part to the transparent resin 100 weight part that forms the fineconcavo-convex structure on the surface, and preferably 5 to 25 weightpart. An anti glare layer may serve as a diffusion layer (viewing angleexpanding function etc.) for diffusing transmitting light through thepolarizing plate and expanding a viewing angle etc.

In addition, the above-mentioned antireflection layer, stickingprevention layer, diffusion layer, anti glare layer, etc. may be builtin the protective film itself, and also they may be prepared as anoptical layer different from the protective layer.

Adhesives are used for adhesion processing of the above describedpolarizing film and the transparent protective film. As adhesives,isocyanate derived adhesives, polyvinyl alcohol derived adhesives,gelatin derived adhesives, vinyl polymers derived latex type, aqueouspolyesters derived adhesives, etc. may be mentioned. The above-describedadhesives are usually used as adhesives comprising aqueous solution, andusually contain solid of 0.5 to 60% by weight.

A polarizing plate of the present invention is manufactured by adheringthe above described transparent protective film and the polarizing filmusing the above described adhesives. The application of adhesives may beperformed to any of the transparent protective film or the polarizingfilm, and may be performed to both of them. After adhered, dryingprocess is given and the adhesion layer comprising applied dry layer isformed. Adhering process of the polarizing film and the transparentprotective film may be performed using a roll laminator etc. Although athickness of the adhesion layer is not especially limited, it is usuallyapproximately 0.1 to 5 μm.

A polarizing plate of the present invention may be used in practical useas an optical film laminated with other optical layers. Although thereis especially no limitation about the optical layers, one layer or twolayers or more of optical layers, which may be used for formation of aliquid crystal display etc., such as a reflector, a transreflectiveplate, a retardation plate (a half wavelength plate and a quarterwavelength plate included), and a viewing angle compensation film, maybe used. Especially preferable polarizing plates are; a reflection typepolarizing plate or a transreflective type polarizing plate in which areflector or a transreflective reflector is further laminated onto apolarizing plate of the present invention; an elliptically polarizingplate or a circular polarizing plate in which a retardation plate isfurther laminated onto the polarizing plate; a wide viewing anglepolarizing plate in which a viewing angle compensation film is furtherlaminated onto the polarizing plate; or a polarizing plate in which abrightness enhancement film is further laminated onto the polarizingplate.

A reflective layer is prepared on a polarizing plate to give areflection type polarizing plate, and this type of plate is used for aliquid crystal display in which an incident light from a view side(display side) is reflected to give a display. This type of plate doesnot require built-in light sources, such as a backlight, but has anadvantage that a liquid crystal display may easily be made thinner. Areflection type polarizing plate may be formed using suitable methods,such as a method in which a reflective layer of metal etc. is, ifrequired, attached to one side of a polarizing plate through atransparent protective layer etc.

As an example of a reflection type polarizing plate, a plate may bementioned on which, if required, a reflective layer is formed using amethod of attaching a foil and vapor deposition film of reflectivemetals, such as aluminum, to one side of a matte treated protectivefilm. Moreover, a different type of plate with a fine concavo-convexstructure on the surface obtained by mixing fine particle into theabove-mentioned protective film, on which a reflective layer ofconcavo-convex structure is prepared, may be mentioned. The reflectivelayer that has the above-mentioned fine concavo-convex structurediffuses incident light by random reflection to prevent directivity andglaring appearance, and has an advantage of controlling unevenness oflight and darkness etc. Moreover, the protective film containing thefine particle has an advantage that unevenness of light and darkness maybe controlled more effectively, as a result that an incident light andits reflected light that is transmitted through the film are diffused. Areflective layer with fine concavo-convex structure on the surfaceeffected by a surface fine concavo-convex structure of a protective filmmay be formed by a method of attaching a metal to the surface of atransparent protective layer directly using, for example, suitablemethods of a vacuum evaporation method, such as a vacuum depositionmethod, an ion plating method, and a sputtering method, and a platingmethod etc.

Instead of a method in which a reflection plate is directly given to theprotective film of the above-mentioned polarizing plate, a reflectionplate may also be used as a reflective sheet constituted by preparing areflective layer on the suitable film for the transparent film. Inaddition, since a reflective layer is usually made of metal, it isdesirable that the reflective side is covered with a protective film ora polarizing plate etc. when used, from a viewpoint of preventingdeterioration in reflectance by oxidation, of maintaining an initialreflectance for a long period of time and of avoiding preparation of aprotective layer separately etc.

In addition, a transreflective type polarizing plate may be obtained bypreparing the above-mentioned reflective layer as a transreflective typereflective layer, such as a half-mirror etc. that reflects and transmitslight. A transreflective type polarizing plate is usually prepared inthe backside of a liquid crystal cell and it may form a liquid crystaldisplay unit of a type in which a picture is displayed by an incidentlight reflected from a view side (display side) when used in acomparatively well-lighted atmosphere. And this unit displays a picture,in a comparatively dark atmosphere, using embedded type light sources,such as a back light built in backside of a transreflective typepolarizing plate. That is, the transreflective type polarizing plate isuseful to obtain of a liquid crystal display of the type that savesenergy of light sources, such as a back light, in a well-lightedatmosphere, and can be used with a built-in light source if needed in acomparatively dark atmosphere etc.

The above-mentioned polarizing plate may be used as ellipticallypolarizing plate or circularly polarizing plate on which the retardationplate is laminated. A description of the above-mentioned ellipticallypolarizing plate or circularly polarizing plate will be made in thefollowing paragraph. These polarizing plates change linearly polarizedlight into elliptically polarized light or circularly polarized light,elliptically polarized light or circularly polarized light into linearlypolarized light or change the polarization direction of linearlypolarization by a function of the retardation plate. As a retardationplate that changes circularly polarized light into linearly polarizedlight or linearly polarized light into circularly polarized light, whatis called a quarter wavelength plate (also called λ/4 plate) is used.Usually, half-wavelength plate (also called λ/2 plate) is used, whenchanging the polarization direction of linearly polarized light.

Elliptically polarizing plate is effectively used to give a monochromedisplay without above-mentioned coloring by compensating (preventing)coloring (blue or yellow color) produced by birefringence of a liquidcrystal layer of a super twisted nematic (STN) type liquid crystaldisplay. Furthermore, a polarizing plate in which three-dimensionalrefractive index is controlled may also preferably compensate (prevent)coloring produced when a screen of a liquid crystal display is viewedfrom an oblique direction. Circularly polarizing plate is effectivelyused, for example, when adjusting a color tone of a picture of areflection type liquid crystal display that provides a colored picture,and it also has function of antireflection. For example, a retardationplate may be used that compensates coloring and viewing angle, etc.caused by birefringence of various wavelength plates or liquid crystallayers etc. Besides, optical characteristics, such as retardation, maybe controlled using laminated layer with two or more sorts ofretardation plates having suitable retardation value according to eachpurpose. As retardation plates, birefringence films formed by stretchingfilms comprising suitable polymers, such as polycarbonates, norbornenetype resins, polyvinyl alcohols, polystyrenes, poly methylmethacrylates, polypropylene; polyallylates and polyamides; orientedfilms comprising liquid crystalline materials, such as liquid crystalpolymer; and films on which an alignment layer of a liquid crystallinematerial is supported may be mentioned. A retardation plate may be aretardation plate that has a proper phase difference according to thepurposes of use, such as various kinds of wavelength plates and platesaiming at compensation of coloring by birefringence of a liquid crystallayer and of visual angle, etc., and may be a retardation plate in whichtwo or more sorts of retardation plates is laminated so that opticalproperties, such as retardation, may be controlled.

The above-mentioned elliptically polarizing plate and an above-mentionedreflected type elliptically polarizing plate are laminated platecombining suitably a polarizing plate or a reflection type polarizingplate with a retardation plate. This type of elliptically polarizingplate etc. may be manufactured by combining a polarizing plate(reflected type) and a retardation plate, and by laminating them one byone separately in the manufacture process of a liquid crystal display.On the other hand, the polarizing plate in which lamination wasbeforehand carried out and was obtained as an optical film, such as anelliptically polarizing plate, is excellent in a stable quality, aworkability in lamination etc., and has an advantage in improvedmanufacturing efficiency of a liquid crystal display.

A viewing angle compensation film is a film for extending viewing angleso that a picture may look comparatively clearly, even when it is viewedfrom an oblique direction not from vertical direction to a screen. Assuch a viewing angle compensation retardation plate, in addition, a filmhaving birefringence property that is processed by uniaxial stretchingor orthogonal bidirectional stretching and a biaxially stretched film asinclined orientation film etc. may be used. As inclined orientationfilm, for example, a film obtained using a method in which a heatshrinking film is adhered to a polymer film, and then the combined filmis heated and stretched or shrinked under a condition of beinginfluenced by a shrinking force, or a film that is oriented in obliquedirection may be mentioned. The viewing angle compensation film issuitably combined for the purpose of prevention of coloring caused bychange of visible angle based on retardation by liquid crystal cell etc.and of expansion of viewing angle with good visibility.

Besides, a compensation plate in which an optical anisotropy layerconsisting of an alignment layer of liquid crystal polymer, especiallyconsisting of an inclined alignment layer of discotic liquid crystalpolymer is supported with triacetyl cellulose film may preferably beused from a viewpoint of attaining a wide viewing angle with goodvisibility.

The polarizing plate with which a polarizing plate and a brightnessenhancement film are adhered together is usually used being prepared ina backside of a liquid crystal cell. A brightness enhancement film showsa characteristic that reflects linearly polarized light with apredetermined polarization axis, or circularly polarized light with apredetermined direction, and that transmits other light, when naturallight by back lights of a liquid crystal display or by reflection from aback-side etc., comes in. The polarizing plate, which is obtained bylaminating a brightness enhancement film to a polarizing plate, thusdoes not transmit light without the predetermined polarization state andreflects it, while obtaining transmitted light with the predeterminedpolarization state by accepting a light from light sources, such as abacklight. This polarizing plate makes the light reflected by thebrightness enhancement film further reversed through the reflectivelayer prepared in the backside and forces the light re-enter into thebrightness enhancement film, and increases the quantity of thetransmitted light through the brightness enhancement film bytransmitting a part or all of the light as light with the predeterminedpolarization state. The polarizing plate simultaneously suppliespolarized light that is difficult to be absorbed in a polarizer, andincreases the quantity of the light usable for a liquid crystal picturedisplay etc., and as a result luminosity may be improved. That is, inthe case where the light enters through a polarizer from backside of aliquid crystal cell by the back light etc. without using a brightnessenhancement film, most of the light, with a polarization directiondifferent from the polarization axis of a polarizer, is absorbed by thepolarizer, and does not transmit through the polarizer. This means thatalthough influenced with the characteristics of the polarizer used,about 50 percent of light is absorbed by the polarizer, the quantity ofthe light usable for a liquid crystal picture display etc. decreases somuch, and a resulting picture displayed becomes dark. A brightnessenhancement film does not enter the light with the polarizing directionabsorbed by the polarizer into the polarizer but reflects the light onceby the brightness enhancement film, and further makes the light reversedthrough the reflective layer etc. prepared in the backside to re-enterthe light into the brightness enhancement film. By this above-mentionedrepeated operation, only when the polarization direction of the lightreflected and reversed between the both becomes to have the polarizationdirection which may pass a polarizer, the brightness enhancement filmtransmits the light to supply it to the polarizer. As a result, thelight from a backlight may be efficiently used for the display of thepicture of a liquid crystal display to obtain a bright screen.

A diffusion plate may also be prepared between brightness enhancementfilm and the above described reflective layer, etc. A polarized lightreflected by the brightness enhancement film goes to the above describedreflective layer etc., and the diffusion plate installed diffusespassing light uniformly and changes the light state into depolarizationat the same time. That is, the diffusion plate returns polarized lightto natural light state. Steps are repeated where light, in theunpolarized state, i.e., natural light state, reflects throughreflective layer and the like, and again goes into brightnessenhancement film through diffusion plate toward reflective layer and thelike. Diffusion plate that returns polarized light to the natural lightstate is installed between brightness enhancement film and the abovedescribed reflective layer, and the like, in this way, and thus auniform and bright screen may be provided while maintaining brightnessof display screen, and simultaneously controlling non-uniformity ofbrightness of the display screen. By preparing such diffusion plate, itis considered that number of repetition times of reflection of a firstincident light increases with sufficient degree to provide uniform andbright display screen conjointly with diffusion function of thediffusion plate.

The suitable films are used as the above-mentioned brightnessenhancement film. Namely, multilayer thin film of a dielectricsubstance; a laminated film that has the characteristics of transmittinga linearly polarized light with a predetermined polarizing axis, and ofreflecting other light, such as the multilayer laminated film of thethin film having a different refractive-index anisotropy; an alignedfilm of cholesteric liquid crystal polymer; a film that has thecharacteristics of reflecting a circularly polarized light with eitherleft-handed or right-handed rotation and transmitting other light, suchas a film on which the aligned cholesteric liquid crystal layer issupported; etc. may be mentioned.

Therefore, in the brightness enhancement film of a type that transmits alinearly polarized light having the above-mentioned predeterminedpolarization axis, by arranging the polarization axis of the transmittedlight and entering the light into a polarizing plate as it is, theabsorption loss by the polarizing plate is controlled and the polarizedlight can be transmitted efficiently. On the other hand, in thebrightness enhancement film of a type that transmits a circularlypolarized light as a cholesteric liquid-crystal layer, the light may beentered into a polarizer as it is, but it is desirable to enter thelight into a polarizer after changing the circularly polarized light toa linearly polarized light through a retardation plate, taking controlan absorption loss into consideration. In addition, a circularlypolarized light is convertible into a linearly polarized light using aquarter wavelength plate as the retardation plate.

A retardation plate that works as a quarter wavelength plate in a widewavelength ranges, such as a visible-light band, is obtained by a methodin which a retardation layer working as a quarter wavelength plate to apale color light with a wavelength of 550 nm is laminated with aretardation layer having other retardation characteristics, such as aretardation layer working as a half-wavelength plate. Therefore, theretardation plate located between a polarizing plate and a brightnessenhancement film may consist of one or more retardation layers.

In addition, also in a cholesteric liquid-crystal layer, a layerreflecting a circularly polarized light in a wide wavelength ranges,such as a visible-light band, may be obtained by adopting aconfiguration structure in which two or more layers with differentreflective wavelength are laminated together. Thus a transmittedcircularly polarized light in a wide wavelength range may be obtainedusing this type of cholesteric liquid-crystal layer.

Moreover, the polarizing plate may consist of multi-layered film oflaminated layers of a polarizing plate and two of more of optical layersas the above-mentioned separated type polarizing plate. Therefore, apolarizing plate may be a reflection type elliptically polarizing plateor a semi-transmission type elliptically polarizing plate, etc. in whichthe above-mentioned reflection type polarizing plate or atransreflective type polarizing plate is combined with above describedretardation plate respectively.

Although an optical film with the above described optical layerlaminated to the polarizing plate may be formed by a method in whichlaminating is separately carried out sequentially in manufacturingprocess of a liquid crystal display etc., an optical film in a form ofbeing laminated beforehand has an outstanding advantage that it hasexcellent stability in quality and assembly workability, etc., and thusmanufacturing processes ability of a liquid crystal display etc. may beraised. Proper adhesion means, such as an adhesive layer, may be usedfor laminating. On the occasion of adhesion of the above describedpolarizing plate and other optical films, the optical axis may be set asa suitable configuration angle according to the target retardationcharacteristics etc.

In the polarizing plate mentioned above and the optical film in which atleast one layer of the polarizing plate is laminated, an adhesive layermay also be prepared for adhesion with other members, such as a liquidcrystal cell etc. As pressure sensitive adhesive that forms adhesivelayer is not especially limited, and, for example, acrylic typepolymers; silicone type polymers; polyesters, polyurethanes, polyamides,polyethers; fluorine type and rubber type polymers may be suitablyselected as a base polymer. Especially, a pressure sensitive adhesivesuch as acrylics type pressure sensitive adhesives may be preferablyused, which is excellent in optical transparency, showing adhesioncharacteristics with moderate wettability, cohesiveness and adhesiveproperty and has outstanding weather resistance, heat resistance, etc.

Moreover, an adhesive layer with low moisture absorption and excellentheat resistance is desirable. This is because those characteristics arerequired in order to prevent foaming and peeling-off phenomena bymoisture absorption, in order to prevent decrease in opticalcharacteristics and curvature of a liquid crystal cell caused by thermalexpansion difference etc. and in order to manufacture a liquid crystaldisplay excellent in durability with high quality.

The adhesive layer may contain additives, for example, such as naturalor synthetic resins, adhesive resins, glass fibers, glass beads, metalpowder, fillers comprising other inorganic powder etc., pigments,colorants and antioxidants. Moreover, it may be an adhesive layer thatcontains fine particle and shows optical diffusion nature.

Proper method may be carried out to attach an adhesive layer to one sideor both sides of the optical film. As an example, about 10 to 40 weight% of the pressure sensitive adhesive solution in which a base polymer orits composition is dissolved or dispersed, for example, toluene or ethylacetate or a mixed solvent of these two solvents is prepared. A methodin which this solution is directly applied on a polarizing plate top oran optical film top using suitable developing methods, such as flowmethod and coating method, or a method in which an adhesive layer isonce formed on a separator, as mentioned above, and is then transferredon a polarizing plate or an optical film may be mentioned.

An adhesive layer may also be prepared on one side or both sides of apolarizing plate or an optical film as a layer in which pressuresensitive adhesives with different composition or different kind etc.are laminated together. Moreover, when adhesive layers are prepared onboth sides, adhesive layers that have different compositions, differentkinds or thickness, etc. may also be used on front side and backside ofa polarizing plate or an optical film. Thickness of an adhesive layermay be suitably determined depending on a purpose of usage or adhesivestrength, etc., and generally is 1 to 500 μm, preferably 5 to 200 μm,and more preferably 10 to 100 μm.

A temporary separator is attached to an exposed side of an adhesivelayer to prevent contamination etc., until it is practically used.Thereby, it can be prevented that foreign matter contacts adhesive layerin usual handling. As a separator, without taking the above-mentionedthickness conditions into consideration, for example, suitableconventional sheet materials that is coated, if necessary, with releaseagents, such as silicone type, long chain alkyl type, fluorine typerelease agents, and molybdenum sulfide may be used. As a suitable sheetmaterial, plastics films, rubber sheets, papers, cloths, no wovenfabrics, nets, foamed sheets and metallic foils or laminated sheetsthereof may be used.

In addition, in the present invention, ultraviolet absorbing propertymay be given to the above-mentioned each layer, such as a polarizer fora polarizing plate, a transparent protective film and an optical filmetc. and an adhesive layer, using a method of adding UV absorbents, suchas salicylic acid ester type compounds, benzophenol type compounds,benzotriazol type compounds, cyano acrylate type compounds, and nickelcomplex salt type compounds.

An optical film of the present invention may be preferably used formanufacturing various equipment, such as liquid crystal display, etc.Assembling of a liquid crystal display may be carried out according toconventional methods. That is, a liquid crystal display is generallymanufactured by suitably assembling several parts such as a liquidcrystal cell, optical films and, if necessity, lighting system, and byincorporating driving circuit. In the present invention, except that anoptical film by the present invention is used, there is especially nolimitation to use any conventional methods. Also any liquid crystal cellof arbitrary type, such as TN type, and STN type, π type may be used.

Suitable liquid crystal displays, such as liquid crystal display withwhich the above-mentioned optical film has been located at one side orboth sides of the liquid crystal cell, and with which a backlight or areflector is used for a lighting system may be manufactured. In thiscase, the optical film by the present invention may be installed in oneside or both sides of the liquid crystal cell. When installing theoptical films in both sides, they may be of the same type or ofdifferent type. Furthermore, in assembling a liquid crystal display,suitable parts, such as diffusion plate, anti-glare layer,antireflection film, protective plate, prism array, lens array sheet,optical diffusion plate, and backlight, may be installed in suitableposition in one layer or two or more layers.

Subsequently, organic electro luminescence equipment (organic ELdisplay) will be explained. Generally, in organic EL display, atransparent electrode, an organic luminescence layer and a metalelectrode are laminated on a transparent substrate in an orderconfiguring an illuminant (organic electro luminescence illuminant).Here, an organic luminescence layer is a laminated material of variousorganic thin films, and much compositions with various combination areknown, for example, a laminated material of hole injection layercomprising triphenylamine derivatives etc., a luminescence layercomprising fluorescent organic solids, such as anthracene; a laminatedmaterial of electronic injection layer comprising such a luminescencelayer and perylene derivatives, etc.; laminated material of these holeinjection layers, luminescence layer, and electronic injection layeretc.

An organic EL display emits light based on a principle that positivehole and electron are injected into an organic luminescence layer byimpressing voltage between a transparent electrode and a metalelectrode, the energy produced by recombination of these positive holesand electrons excites fluorescent substance, and subsequently light isemitted when excited fluorescent substance returns to ground state. Amechanism called recombination which takes place in a intermediateprocess is the same as a mechanism in common diodes, and, as isexpected, there is a strong non-linear relationship between electriccurrent and luminescence strength accompanied by rectification nature toapplied voltage.

In an organic EL display, in order to take out luminescence in anorganic luminescence layer, at least one electrode must be transparent.The transparent electrode usually formed with transparent electricconductor, such as indium tin oxide (ITO), is used as an anode. On theother hand, in order to make electronic injection easier and to increaseluminescence efficiency, it is important that a substance with smallwork function is used for cathode, and metal electrodes, such as Mg—Agand Al—Li, are usually used.

In organic EL display of such a configuration, an organic luminescencelayer is formed by a very thin film about 10 nm in thickness. For thisreason, light is transmitted nearly completely through organicluminescence layer as through transparent electrode. Consequently, sincethe light that enters, when light is not emitted, as incident light froma surface of a transparent substrate and is transmitted through atransparent electrode and an organic luminescence layer and then isreflected by a metal electrode, appears in front surface side of thetransparent substrate again, a display side of the organic EL displaylooks like mirror if viewed from outside.

In an organic EL display containing an organic electro luminescenceilluminant equipped with a transparent electrode on a surface side of anorganic luminescence layer that emits light by impression of voltage,and at the same time equipped with a metal electrode on a back side oforganic luminescence layer, a retardation plate may be installed betweenthese transparent electrodes and a polarizing plate, while preparing thepolarizing plate on the surface side of the transparent electrode.

Since the retardation plate and the polarizing plate have functionpolarizing the light that has entered as incident light from outside andhas been reflected by the metal electrode, they have an effect of makingthe mirror surface of metal electrode not visible from outside by thepolarization action. If a retardation plate is configured with a quarterwavelength plate and the angle between the two polarization directionsof the polarizing plate and the retardation plate is adjusted to π/4,the mirror surface of the metal electrode may be completely covered.

This means that only linearly polarized light component of the externallight that enters as incident light into this organic EL display istransmitted with the work of polarizing plate. This linearly polarizedlight generally gives an elliptically polarized light by the retardationplate, and especially the retardation plate is a quarter wavelengthplate, and moreover when the angle between the two polarizationdirections of the polarizing plate and the retardation plate is adjustedto π/4, it gives a circularly polarized light.

This circularly polarized light is transmitted through the transparentsubstrate, the transparent electrode and the organic thin film, and isreflected by the metal electrode, and then is transmitted through theorganic thin film, the transparent electrode and the transparentsubstrate again, and is turned into a linearly polarized light againwith the retardation plate. And since this linearly polarized light liesat right angles to the polarization direction of the polarizing plate,it cannot be transmitted through the polarizing plate. As the result,mirror surface of the metal electrode may be completely covered.

EXAMPLES

Description will be given of the invention in a more detailed waydescribing examples and it should be understood that the invention isnot limited to any of the examples.

Example 1

Gradually dissolved into water while heated and stirred were 100 partsby weight of polyvinyl alcohol having a polymerization degree of 2400(with a transmittance of 88% measured on a sample having a thickness of1 mm) and 10 parts by weight of glycerin to thereby obtain a 10 wt %polyvinyl alcohol aqueous solution. Mixed into 10 parts by weight of theobtained polyvinyl alcohol aqueous solution was 4 parts by weight of a 1wt % aqueous dispersion of ultrafine silver particles (an averageparticle diameter of 20 nm) and the mixture was sufficiently stirred toprepare a mixed solution. Then, the mixed solution was extended on aflat plate on which a mold release treatment had been applied in advancewith an applicator to a thickness after drying of 75 μm and was dried at50° C. for 1 hour to obtain a polyvinyl alcohol film in which ultrafinesilver particles were dispersed. The obtained polyvinyl alcohol film wasuniaxially stretched at a stretch ratio of 3 while being brought intocontact with a metal roll heated at 100° C. to thereby obtain apolarizer having a thickness of 30 μm. A transmittance of the film afterstretching was 88%. The stretched film was in light yellow due toabsorption by ultrafine silver particles and exhibited a dichroicperformance.

An average particle diameter and an aspect ratio of domains formed withfine metallic particles were measured on the obtained polarizer. Anaverage particle diameter and an aspect ratio were measured with TEM.The average particle diameter was 25 nm and the aspect ratio was 1.3. Anabsorption characteristic of the obtained polarizer was measured withthe result that increase in absorption was confirmed in the vicinity of400 nm. Note that measurement of an absorption characteristic wasperformed with U-4100 manufactured by Hitachi, Ltd.

(Physical Property of Polarizer)

A birefringence itself of a film made from a polyvinyl alcohol, whichwas a matrix material of a polarizer, was unable to be measured, but fora film stretched in the same condition as the above except for adding nofine silver particles a retardation (Δn·d) and d (Δn: birefringence, d:film thickness) were firstly measured with an automatic birefringenceanalyzer KOBRA-21ADH, manufactured by Oji Scientific Instruments andthereafter, Δn was secondly obtained to be 0.03.

(Absorption Spectrum of Polarizer)

Absorption spectra in a case where polarized light enters on theobtained polarizer were measured. Absorption spectra are shown inFIG. 1. Measurement of an absorption spectrum was performed with aspectrophotometer U4100 manufactured by Hitachi, Ltd. with installmentof a Glan-Thomspn polarization prism. In a case where the incidentpolarization plane was, as shown in FIG. 1, in parallel to the stretchdirection (MD polarized light), the absorption peak wavelength was atthe longest wavelength (λ1: 438 nm), while the peak wavelength shiftedto the short wavelength side (for example, 45 degrees polarized light)as an azimuth of the incident polarization plane rotated and theabsorption peak took the shortest wavelength (λ2: 410 nm) in polarizedlight (TD polarized light) in a direction perpendicular to the stretchdirection. The polarizer eventually produced polarized light and(λ1−2)=28 nm was obtained.

Example 2

A polarizer was obtained in a similar way to that in Example 1 with theexception that in Example 1, fine silver particles were replaced withfine gold particles to thereby obtain a polarizer. Transmittance of astretched film was 88%. The stretched film was in light red color due toabsorption by ultrafine gold particles and exhibits a dichroicperformance. An average particle diameter of domains formed with finemetallic particles in the obtained polarizer was 25 nm and an aspectratio thereof was 1.2.

Comparative Example 1

Used was an iodine-based polarizer sold on the market having atransmittance of 43% and a polarization degree of 99.95% after two viewfield XYZ correction according to JIS Z 8701, wherein a polyvinylalcohol film having a transmittance of 88% was used as the matrixmaterial.

Comparative Example 2

A film obtained by dispersing fine silver particles in polyimide havinga transmittance 68% at the same content as in Example 1 was stretched ata stretch ratio of 1.1 to obtain a polarizer. The stretched film was indeep yellow color due to coloration of polyimide and absorption byultrafine silver particles and exhibits a dichroic performance.

The following evaluations were performed on the polarizers of Examples 1to 2 and Comparative Examples 1 to 2. The results of the evaluations areshown in Table 1.

(Transmittance)

A transmittance of a polymer matrix was a total transmittance (%) for awavelength of 550 nm measured with U-4100 manufactured by Hitachi, Ltd.

(Heat Resistance)

A polarizer was left as it is in an environment at 100° C. for 24 hoursto dry and thereafter, the polarizer was visually observed to evaluateusing the following criteria.

-   O: decoloration and alteration in color are not observed visually.-   x: decoloration and alteration in color can be observed visually.

TABLE 1 Transmittance of polymer matrix (%) Heat resistance Example 1 88∘ Example 2 88 ∘ Comparative 88 x Example 1 Comparative 68 ∘ Example 2

Example 3

Dissolved into a toluene was 100 parts by weight of a liquid crystalmonomer having one acryloyl group in a molecule (forming a nematicliquid crystal phase at a temperature of 90 to 190° C.) and added intothe solution were 5 parts by weight of a photopolymerization initiator(IRGACURE 907 manufactured by Ciba Specialty Chemicals) and 0.5 parts byweight of a leveling agent (BYK-361) to prepare a solution of a liquidcrystal monomer having a concentration of 20 wt %. Mixed into thesolution was 1 part by weight of about 1 wt % dispersion liquid ofultrafine silver particles obtained by dispersing the ultrafine silverparticles (an average particle diameter of 10 nm) into toluene and themixture was sufficiently stirred to prepare a mixed solution containingultrafine silver particles at a concentration of about 1%.

The mixed solution was coated on an alignment film obtained by rubbingtreated a thin layer made from polyvinyl alcohol formed on a glasssubstrate by spin coating and was dried at 110° C. for 3 min. Andirradiation was performed with UV for UV polymerization to therebyobtain a polarizer having a thickness of 2 μm.

An aspect ratio of a domain formed with fine metallic particles wasmeasured on the obtained polarizer. An average particle diameter and anaspect ratio were measured with TEM. The aspect ratio was 1.3. Anabsorption characteristic was measured of the obtained polarizer withthe result that increase in absorption at 420 nm was confirmed. Notethat measurement of an absorption characteristic was performed withU-4100 manufactured by Hitachi, Ltd.

Example 4

A liquid crystal polymer of a side chain type having a cyanobiphenylgroup (forming a nematic phase at 70 to 190° C.) was dissolved intotoluene to thereby prepare a solution at a concentration of 20 wt %.Mixed into the solution was 1 part by weight of a 20 wt % dispersionliquid of ultrafine silver particles (an average particle diameter of 10nm) obtained by dispersing the ultrafine silver particles into tolueneand the mixture was sufficiently stirred to prepare a mixed solutionhaving ultrafine particles at a concentration of about 1%.

The mixed solution was coated, by spin coating, on an alignment filmobtained by rubbing treating a thin layer of a polyvinyl alcohol formedon a glass substrate and was dried at 110° C. for 3 min to therebyobtain a polarizer having a thickness of 2 μm.

An aspect ratio of a domain formed with fine metallic particles wasmeasured on each of the obtained polarizers. An average particlediameter and an aspect ratio were measured with TEM. The aspect ratiowas 1.3. An absorption characteristic was measured of the obtainedpolarizers with the result that increases in absorption were confirmedin the vicinities of 420 nm and 550 nm.

Evaluation of heat resistance was performed on the polarizers ofExamples 3 to 4 in the same manner as the above procedure. The resultsof the evaluation are shown in Table 2.

TABLE 2 Heat resistance Example 3 ∘ Example 4 ∘

INDUSTRIAL APPLICABILITY

The invention is useful as a polarizer and a polarizing plate and anoptical film using the polarizer or polarizers can be preferably appliedto image displays such as a liquid crystal display, an organic ELdisplay, CRT and PDP.

1. A polarizer composed of a film comprising a structure in which fine metallic particles is dispersed in a polymer matrix, wherein a polymer forming the polymer matrix is a translucent polymer having a light transmittance of 88% or more when measured thereof with a thickness of 1 mm and the film is uniaxially stretched, a domain formed with fine metallic particles has an average particle diameter of 100 nm or less and an aspect ratio (a ratio of a maximum length/a minimum length) of less than 1.5, wherein the fine metallic particles are gold fine particles or silver fine particles and the translucent polymer has uniaxial birefringence due to uniaxial stretching; and the polarizer has an absorption spectrum with an absorption peak at a given wavelength, measured when polarized light incidences thereon, wherein if an azimuth of an incident polarization plane is altered relative to the polarizer, the absorption peak wavelength shifts in accordance with an alteration in the azimuth, in a case where an azimuth of the incident polarization plane relative to the polarizer is altered, if an azimuth of the incident polarization plane is 0 degree when an absorption peak wavelength of an absorption spectrum that is measured is the longest wavelength, which is referred to as λ1, by definition, if an azimuth of the polarization plane is gradually increased from 0 degree, a value of the absorption peak wavelength shifts to the short wavelength side in accordance with the increase, when an azimuth of the incident polarization plane is 90 degrees, a value of the absorption peak wavelength is the shortest wavelength, which is referred to as λ2, by definition, and satisfying a relation of(λ1−λ2)=10 to 50 nm.
 2. A fabrication method for the polarizer according to claim 1, comprising steps of: forming a film with a mixed solution comprising fine metallic particles obtained by dispersing fine metallic particles in a solution containing a translucent polymer having a light transmittance of 88% or more when measured thereof with a thickness of 1 mm and thereafter, uniaxially stretching the film.
 3. A polarizing plate in which a transparent protective layer is provided on at least one surface of the polarizer according to claim
 1. 4. An optical film comprising the polarizing plate according to claim 3 as a laminate.
 5. An image display comprising the polarizing plate according to claim
 3. 6. An optical film comprising one polarizer according to claim
 1. 7. An image display comprising the optical film according to claim
 6. 8. An image display comprising one polarizer according to claim
 1. 9. The polarizer according to claim 1, wherein a content of fine metallic particles dispersed in the matrix is 0.1 to 10 parts by weight relative to 100 parts by weight of the matrix materials.
 10. The polarizer according to claim 1, wherein said fine metallic particles are not aligned within the polymer matrix.
 11. The polarizer according to claim 1, wherein the average particle diameter is 25 nm and the aspect ratio is 1.3.
 12. The polarizer according to claim 1, wherein the film has a stretch ratio of 3 to 30 times.
 13. A polarizer in which fine metallic particles is dispersed in a matrix formed with a liquid crystalline material, wherein a domain formed with fine metallic particles has an average particle diameter of 100 nm or less and an aspect ratio (a ratio of a maximum length/a minimum length) of or less than 1.5, wherein the fine metallic particles are gold fine particles or silver fine particles; and the polarizer has an absorption spectrum with an absorption peak at a given wavelength, measured when polarized light incidences thereon, wherein if an azimuth of an incident polarization plane is altered relative to the polarizer, the absorption peak wavelength shifts in accordance with an alteration in the azimuth, in a case where an azimuth of the incident polarization plane relative to the polarizer is altered, if an azimuth of the incident polarization plane is 0 degree when an absorption peak wavelength of an absorption spectrum that is measured is the longest wavelength, which is referred to as λ1, by definition, if an azimuth of the polarization plane is gradually increased from 0 degree, a value of the absorption peak wavelength shifts to the short wavelength side in accordance with the increase, when an azimuth of the incident polarization plane is 90 degrees, a value of the absorption peak wavelength is the shortest wavelength, which is referred to as λ2, by definition, and satisfying a relation of(λ1−λ2)=10 to 50 nm.
 14. The polarizer according to claim 13, wherein the liquid crystalline material is uniaxially aligned.
 15. The polarizer according to claim 13, wherein the liquid crystalline material is a liquid crystal polymer.
 16. The fabrication method for the polarizer according to claim 13, comprising step of: forming a film with a mixed solution obtained by dispersing fine metallic particles in a solution containing a liquid crystalline material.
 17. The polarizer according to claim 13, wherein a content of fine metallic particles dispersed in the matrix is 0.1 to 10 parts by weight relative to 100 parts by weight of the matrix materials.
 18. The polarizer according to claim 13, wherein said fine metallic particles are not aligned within the liquid crystalline material matrix.
 19. A polarizer composed of a film in which fine metallic particles is dispersed in a translucent polymer having a birefringence in the film plane, wherein a domain formed with fine metallic particles has an average particle diameter of 100 nm or less and an aspect ratio (a ratio of a maximum length/a minimum length) of less than 1.5, the polarizer has an absorption spectrum with an absorption peak at a given wavelength, measured when polarized light incidences thereon, wherein if an azimuth of an incident polarization plane is altered relative to the polarizer, the absorption peak wavelength shifts in accordance with an alteration in the azimuth, and wherein the fine metallic particles are gold fine particles or silver fine particles and the translucent polymer has uniaxial birefringence due to uniaxial stretching in a case where an azimuth of the incident polarization plane relative to the polarizer is altered, if an azimuth of the incident polarization plane is 0 degree when an absorption peak wavelength of an absorption spectrum that is measured is the longest wavelength, which is referred to as λ1, by definition, if an azimuth of the polarization plane is gradually increased from 0 degree, a value of the absorption peak wavelength shifts to the short wavelength side in accordance with the increase when an azimuth of the incident polarization plane is 90 degrees, a value of the absorption peak wavelength is the shortest wavelength, which is referred to as λ2, by definition, and satisfying a relation of(λ1−λ2)=10 to 50 nm.
 20. The polarizer according to claim 19, wherein a content of fine metallic particles dispersed in the matrix is 0.1 to 10 parts by weight relative to 100 parts by weight of the matrix materials.
 21. The polarizer according to claim 19, wherein said fine metallic particles are not aligned with the polymer matrix.
 22. The polarizer according to claim 19, wherein the film has a stretch ratio of 3 to 30 times. 